Tourniquet or No Tourniquet: What Is the Price to Pay in Primary TKA?

One of the first decisions required in the performance of total knee arthroplasty (TKA) is whether to use an inflated tourniquet, to not use a tourniquet, or to use a tourniquet selectively, during cementation. Surgeons will be influenced by their previous experience and training, but hopefully will also look to results from well-designed orthopaedic trials to inform their opinions and shape their decision. The current study by Peng et al. provides this opportunity, with an evaluation both of component fixation and of perioperative consequences with respect to tourniquet use. The authors report the results of a longitudinal, prospective, randomized controlled trial (RCT) looking at the issue of cement penetration in TKA for primary knee osteoarthritis. Procedures were performed in 2018 and 2019 by 2 experienced surgeons using similar techniques: a medial parapatellar approach with the patient under general anesthesia with controlled hypotension using preoperative intravenous tranexamic acid (IV TXA) and postoperative IV TXA at 2 intervals. Randomization by envelope was performed preoperatively, with patients assigned to 1 of 3 groups: full tourniquet use, no tourniquet use, or tourniquet use exclusively during cementation. In all cases of tourniquet use, the tourniquet was released after the implants were fixed. The study had 2 primary outcomes, the first of which was intraosseous cement penetration at the tibial and femoral bone-prosthesis interfaces, evaluated by 3D reconstruction using metal artifact reduction-computed tomography (MAR-CT) images. Multiple peer-reviewed studies have shown that MAR algorithms improve the ability to assess cement penetration, with a track record that includes use after TKA1–3. The summary conclusion of the study is that constant tourniquet use did not provide benefit with respect to cement penetration at surgery or with respect to aseptic loosening (defined as progressive radiolucent lines [>2 mm]) on conventional radiographs at 5-year follow-up. In addition to their original question regarding tourniquet use, the authors carefully probed patient characteristics that might influence cement penetration. The reader is encouraged to peruse the supplementary materials to gain a more detailed understanding of what exactly was done to evaluate the 3 groups. Elevated bone turnover, particularly as assessed by resorption markers, predicts accelerated bone loss and microstructural deterioration4,5. Biomarkers were measured preoperatively, and no significant differences were observed. In addition, trabecular bone permeability, as defined by fluid dynamics, quantifies resistance to fluid flow through bone pores, directly reflecting trabecular microstructure (pore size, connectivity, and shape). As the authors note, mean flow correlates with overall porosity, while peak flow reflects minimal pore size6–8. This evaluation did not reveal any differences among the 3 groups preoperatively, supporting the contention that bone quality was successfully balanced by the randomization process and should not have influenced the final study conclusion. One will note the discrepancy in the distribution by sex in this TKA cohort. This may be a regional effect and/or a practice pattern that reflects the recruitment of more female than male candidates. This is acknowledged in the paper as a limitation with respect to whether the findings could reasonably be extrapolated to males, and readers are left to decide for themselves. The present study was designed to identify some of the secondary consequences of the tourniquet decision. These are summarized in Supplementary Table S4, with expected differences in tourniquet time and significantly lower levels of inflammatory markers in the no-tourniquet group observed. There were also statistical advantages observed for the no-tourniquet group in terms of pain reported on days 1 and 3 and, compared with the full-tourniquet group, in terms of range of motion and even hospital stay, but these differences were quite small nominally, and none would reach what most would consider clinical importance. Surgeons have had to rethink their processes as economics and advances in perioperative care continue to push toward outpatient TKA. The trend toward cementless TKA may eventually make the results of the current study perhaps less relevant. Nonetheless, the study does provide an anchor for surgeons who wish to inform their decisions on tourniquet use in cemented TKA, as they balance the considerations of a few more minutes of operative time and increased intraoperative blood loss with the benefits of a small decrease in perioperative pain, without concern for early to medium-term radiographic component stability. We look forward to the replication of the current study in an ambulatory setting with a more balanced sex distribution, consistent with many other orthopaedic practices.